Ryo Shimano

In high-energy physics, the Higgs field couples to gauge bosons and fermions and gives mass to their elementary excitations. Experimentally, such couplings can be inferred from the decay product of the Higgs boson, i.e., the scalar (amplitude) excitation of the Higgs field. In superconductors, Cooper pairs bear a close analogy to the Higgs field. Interaction between the Cooper pairs and other degrees of freedom provides dissipation channels for the amplitude mode, which may reveal important info

We report on the observation of electron-hole ( e-h) liquid (EHL) in diamond by time-resolved luminescence measurements under an intense femtosecond photoexcitation above the band gap. The EHL luminescence band is observed below the e-h plasma band, showing a finite rise time of several tens of picoseconds. The rise time, which corresponds to the nucleation and the growth of the e-h droplets, plummets on approaching the EHL critical temperature. Time-resolved spectral shape analysis reveals a ve

We report on the time-domain terahertz (THz) magneto-optical Kerr spectroscopy in the frequency range from 0.5 to 2.5 THz. The developed technique employs reflection geometry, enabling high-frequency noncontact Hall measurements in opaque samples. We also present a method to reveal the off-diagonal component of the complex dielectric tensor from the measured polarization-dependent THz wave forms. At a static magnetic field of 0.48 T, a large Kerr rotation over 10° originating from magnetoplasma

Wave vector selective ac Stark effect of the ${\mathrm{\ensuremath{\Gamma}}}_{1}$-biexciton state is clearly observed in the steady state regime. The biexciton line splits into two lines with resonant pumping between ${\mathit{Z}}_{3}$ exciton polariton and the biexciton state. From the splitting energy, we have obtained the relevant dipole moment of 4.2e \AA{}. Observed energy of the dressed state coincides with the value derived from the model with strict energy and quasimomentum selection rul

We report on the observation of Faraday rotation in the terahertz frequency range in a thin film of itinerant ferromagnet, SrRuO3. As optical counterpart of the anomalous Hall effect (AHE), the complex optical Hall conductivity spectrum σxy(ω) was extracted from the Faraday rotation and ellipticity spectrum. The temperature and frequency (ω) dependences of σxy(ω) in the terahertz regime are consistently connected with the dc AHE. A clear resonance structure is identified in the σxy(ω) spectrum r

Abstract Illumination of light on matter normally causes heating and destroys the ordered ground states. Despite this common understanding, recent advances in ultrafast light sources have enabled the non-thermal control of quantum phases. Here, we report the light-induced enhancement of superconductivity in a thin film of an iron chalcogenide FeSe 0.5 Te 0.5 , which exhibits multiple quantum condensates associated with the multi-orbital character. Upon the photoexcitation, we observed a transien

We report on frequency tunable circular polarization control of THz radiation. The technique is based on the relative phase control of two THz pulses that are generated from optical rectification of ultrashort optical pulses in a ZnTe crystal. By changing the temporal separation of the optical pump pulses, continuous control of circular polarization from right to left is achieved in the frequency range from 0.3 to 2.5 THz. The developed scheme shows a potential application for sensitive detectio